Date of Award
Doctor of Philosophy (PhD)
The malaria parasite, Plasmodium falciparum, infects hundreds of millions of people per year and causes hundreds of thousands of deaths. Within the host red blood cell, the parasite relies on glycolysis for energy and synthesis of essential biomolecules. One such anabolic fate of glucose is the synthesis of isoprenoids, a broad and essential class of compounds that participate in a variety of cellular functions. In the face of ever-evolving drug resistance, new inhibitors and better understanding of parasite metabolism are required. The antibiotic fosmidomycin (FSM) targets the methylerythritol phosphate pathway for isoprenoid synthesis and is a well-validated inhibitor of P. falciparum growth. A forward selection for FSM resistance generated a number of parasite strains with increased drug tolerance. We identify mutations in two members of the haloacid dehalogenase-like hydrolase (HAD) superfamily, PfHAD1 and PfHAD2, as causal for resistance. Enzymatic characterization and metabolic profiling reveal that these mutations are deleterious and confirm the role of PfHAD1 and PfHAD2 as novel negative regulators of glucose and isoprenoid metabolism. Despite their homology and shared role in FSM resistance, PfHAD1, a sugar phosphatase, and PfHAD2, a purine nucleotidase, appear to mediate FSM resistance via distinct enzymatic mechanisms. To further understand the role of PfHADs as metabolic regulators, we harness a growth defect in FSM-resistant PfHAD2 mutants to select for suppressors of FSM resistance. We identify suppressor mutations in the key glycolytic enzyme phosphofructokinase (PfPFK9) and describe the effect of these mutations on enzyme function and parasite metabolism.
Chair and Committee
Audrey R. Odom John
David Sibley, Susan K. Dutcher, Joseph M. Jez, Gautam Dantas
Guggisberg, Ann Marie, "Discovery and characterization of a novel class of metabolic regulators in the malaria parasite Plasmodium falciparum" (2016). Arts & Sciences Electronic Theses and Dissertations. 989.